This invention relates generally to an absorbent article such as a disposable diaper and an infant's toilet training pant provided with an indicator allowing a parent or a care personnel of a wearer to perceive whether bodily fluids have been discharged or not.
There have already been proposed disposable diaper comprising a liquid-pervious topsheet, a light-transmissive and liquid-impervious backsheet and a liquid-absorbent core interposed between these sheets, wherein the diaper is provided between the backsheet and the core with an indicator adapted to make discharge of bodily fluids visible when the indicator is wetted with bodily fluids. The diaper is disclosed, for example, in Japanese Unexamined Patent Application Publication No. 1997-140742 (hereinafter referred to as “Reference”). The indicator has a belt-like shape which is relatively long in a transverse direction and extends in the transverse direction in a longitudinal midsection of a front waist region.
The indicator comprises a base sheet made of paper, a first coating layer intermittently laid on the inner surface of the base sheet facing the core and a while or milky white second coating layer intermittently laid on the outer surface of the base sheet facing the backsheet. The first coating layer has a color tone different from those of the backsheet, the base sheet and the second coating layer and contains light scattering materials such as silica or alumina in the form of microscopic particles. The second coating layer also contains light scattering materials such as silica or alumina in the form of microscopic particles and utilizes diffused reflection of light to cover up the first coating layer. When bodily fluids discharged on the diaper put on the wearer's body permeate the first and second coating layers, light scattering in both the first and second coating layers is so reduced that the effect to cover up the first coating layer is deteriorated. Consequentially, the first coating layer becomes visible through the base sheet and the second coating layer from the outside of the backsheet. In this way, the parent or the care personnel can visually determine from the outside of the backsheet whether bodily fluids have been discharged or not on the diaper.
In the case of the diaper disclosed in Reference, bodily fluids having been absorbed by the core permeate the first coating layer and then the base sheet and thereafter permeate the second coating layer from the base sheet. In other words, a certain time is taken before bodily fluids having been discharged on the diaper reach the second coating layer. In addition, no capillary action occurs in the second coating layer and it is difficult for the second coating layer to absorb bodily fluids at once. Even after bodily fluids have reached the second coating layer, a certain time is taken before the light scattering in the second coating layer is significantly reduced. Consequentially, it is always likely that the parent or the care personnel might not perceive discharge of bodily fluids immediately after it has occurred since a certain time is taken until the first coating layer becomes visible after bodily fluids have been discharged.